1. Field of the Invention
The invention relates to a method for streaming multi channel digital isochronous data for wireless transmission for mainly audio purposes. The invention relates also to a system for streaming digital serial audio data for wireless transmission for audio purposes.
The invention relates to an error control method and system and a synchronization method and system.
The subject of this invention is typically a system with the associated apparatus and method for the isochronous, electromagnetic disturbance resistant, wireless transfer of highest studio-quality multi-channel digital audio. This same method can also be used as the basis of the multicast transmission of other digital information with the same kind of real-time and bandwidth requirements such as live digital video and television signal distribution over the local area.
2. Brief Discussion of the Related Art
With the currently known technique, the studio-quality multi-channel digital audio signal is first converted to the analog form and then transferred to loudspeakers with the per-channel electrical cables. Also, a digital transmission method in electrical cables or optical fibres, is known. If the loudspeakers are passive, an additional amplifier for each loudspeaker is required to amplify the signal power at the transmitter and to feed the transmission cable line with enough power to drive the loudspeakers at the appropriate sound level. All these manipulations, as well as the physical analog transmission path itself, inject several degrading effect such as noise, interference, distortion, group delays, amplitude and phase errors, to the quality of the original signal. The cabling is often clumsy and can be messy looking. With careful design of cables and their wiring layout, these effects can be limited to some extent but seldom completely overcome. The number and bulkiness of the cables, the need for careful design and tedious installation work increase the costs as well as required skills and time. Cables and their electromechanical connectors are also prone to mechanical faults, which are hard to find and fix. These problems are especially harmful in public performances when the performers and often even the audience move among the cables. Under these conditions, there can be a real hazard of harm and injury with the cabling. During artistic tours, the audio equipment is installed and uninstalled frequently to and from varying environments, which multiplies these problems, efforts, and costs.
The use of active loudspeakers, having integrated and optimised amplifiers within them, simplifies the situation to some degree. The analog signals can now be of lower power level and the more noise and interference resistant differential signalling can be readily employed. The generation of multi-channel differential signals requires, however, rather expensive high-quality analog electronics plus costly differential cabling and connectors.
The currently available wireless audio distribution systems are non-standard radio or infrared solutions typically using lossy audio compression methods thus resulting compromised performance. They are therefore mainly used for supportive purposes such as for rear speakers in home theatres.